Heretofore, there have been various types of internal combustion engines designed and some of these engines have had variable displacement pistons provided therein, utilizing an articulated connecting rod linkage to vary the stroke of the engine piston in accordance with engine operating conditions and U.S. Pat. No. 4,133,094 shows a combustion engine of that type. Yet another type of a variable displacement reciprocating piston machine is shown in U.S. Pat. No. 4,112,826 which discloses correlating and controlling motion in two associated pistons simultaneously. The compression ratio of the internal combustion engine of U.S. Pat. No. 4,092,957 is controlled by providing two opposed pistons acting in a cylinder, the pistons being connected by a rocker beam to a crankshaft. Simple links and levers joined together by pin joints form the control for a variable stroke piston engine in U.S. Pat. No. 2,909,163 and a similar structure is present in the variable compression ratio engine of U.S. Pat. No. 2,909,164.
The foregoing patents are representative of previously proposed and patented structures in the field of endeavoring to provide a substantially constant compression, variable stroke piston, internal combustion engine.
While it has been known that substantial improvement in part-load efficiencies can be made by increasing the compression ratio as the engine is throttled down to lower speeds, yet it has been very difficult, if not impossible, to provide any efficient, practical type of an internal combustion engine, that obtains a desirable, substantially constant compression ratio at different operating speeds.
The foregoing types of engines have, in general, had either very complicated mechanisms involved in their design, or else the variability of the stroke has been quite limited.